U.S. Pat. Nos. 3,453,745 and 3,552,036 disclose electronically operated means to simulate, control, and modify ECG signals. The signals are displayed on standard osciloscope-type monitors. However, these patents only address means to simulate ECG signals.
U.S. Pat. No. 4,091,549 discloses means to trace heart electrical activity through specific points of a heart by means of illumination of specific parts of an illustration of a heart.
U.S. Pat. No. 4,254,562 discloses means to trace blood flow through specific points of a heart model or other component of a living organism.